'''Joel Asaph Allen''' (July 19, 1838 – August 29, 1921) was an United States|American zoology|zoologist
He became the first president of the American Ornithologists' Union
, the first curator of bird
s and mammal
s at the American Museum of Natural History
, and the first head of that museum's Department of Ornithology.
He is remembered for Allen's rule
, which states that the bodies of endotherms
(warm-blooded animals) vary in shape with climate, having increased surface area in hot climates to lose heat, and minimized surface area in cold climates, to conserve heat.